I did a search and couldn't find anyone with the exact same problem, so I figure I'll post it here for a possible solution. I just installed Fedora core 64 last night and after the intial install, audio was working fine (albeit a tad loud at first....lol). About 10 minutes later, it stopped working entirely with this install. I upgraded the core after that and it still doesn't work. I am using a cHaintech VNF3-250 motherboard with the Cmedia CM19761A 5.1 audio chip. I did notice that when I went to the auto-detect mode for my audio it lists the soundcard model as a Corporation NForce3 250Gb and the module as: snd-intel8x0. Not sure if that helps (or is even correct), but will run any test required to get this working. Be patient....completely new to the Linux world and may take a bit of coaching here to get things right.

Forgot to add:

00:00.0 Host bridge: nVidia Corporation: Unknown device 00e1 (rev a1)
00:01.0 ISA bridge: nVidia Corporation: Unknown device 00e0 (rev a2)
00:01.1 SMBus: nVidia Corporation nForce 250Gb PCI System Management (rev a1)
00:02.0 USB Controller: nVidia Corporation CK8S USB Controller (rev a1)
00:02.1 USB Controller: nVidia Corporation CK8S USB Controller (rev a1)
00:02.2 USB Controller: nVidia Corporation CK8S USB Controller (rev a2)
00:06.0 Multimedia audio controller: nVidia Corporation nForce3 250Gb AC'97 Audio Controller (rev a1)
00:08.0 IDE interface: nVidia Corporation CK8S Parallel ATA Controller (v2.5) (rev a2)
00:0a.0 IDE interface: nVidia Corporation CK8S Serial ATA Controller (v2.5) (rev a2)
00:0b.0 PCI bridge: nVidia Corporation nForce3 250Gb AGP Host to PCI Bridge (rev a2)
00:0e.0 PCI bridge: nVidia Corporation nForce3 250Gb PCI-to-PCI Bridge (rev a2)
00:18.0 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] HyperTransport Technology Configuration
00:18.1 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Address Map
00:18.2 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] DRAM Controller
00:18.3 Host bridge: Advanced Micro Devices [AMD] K8 [Athlon64/Opteron] Miscellaneous Control
01:00.0 VGA compatible controller: ATI Technologies Inc Radeon R350 [Radeon 9800 Pro]
01:00.1 Display controller: ATI Technologies Inc Radeon R350 [Radeon 9800 Pro] (Secondary)
02:0d.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8139/8139C/8139C+ (rev 10)

any suggestions would be greatly appreciated. I have checked the mixer control panel and made sure that all settings for audio o/p were un-muted and turned up, so I know that isn't the issue.